Addition agents for mineral oil lubricants



Patented June 7, 1949 ADDITION AGENTS FOR LUBRICANT gflNERAL OIL Herschel G. Smith, Wallingford, and Troy L. Cantrell, Lansdowne, Pa., and John G. Peters, Au-

dubon, N. J assignors to Gulf Oil Corporation, Pittsburgh, Pa., a corporation of Pennsylvania No Drawing. Application June 12, 1947, Serial No. 754,269

21 Claims (Cl. 252-42.'l)

This invention relates to addition agents for mineral oil lubricants, and more particularly, it relates to addition agents which confer improved detergent and corrosion-inhibitingproperties on mineral oil lubricants.

In the lubrication of internal combustion engines of all types, particularly when severe operating conditions are encountered, mineral lubricating oils frequently prove unsatisfactory because they tend to deposit varnish, gum and sludge on the engine surfaces, such as the cylinder walls, pistons and rings, and also to induce corrosion of bearing materials. These problems have become increasingly serious because of the trend toward higher efliciency or higher power output per unit weight of engine, which results in conditions tending to accelerate deteriorating mnu-- ences on the mineral oil lubricant.

The formation of so-called varnishes and sludges on engine surfaces is a result of oxidation effects on the lubricating oils. The presence of such engine deposits is detrimental for many reasons. These substances increase ring sticking and accelerate the formation of further deposits on piston surfaces and fixed parts of the combustion chamber. The sludges formed in the crank case of the engine increase the rate of corrosion of bearing surfaces, especially of bearing alloys of the type now in use.

In the lubrication of steam turbines, the problems become more acute because of the presence of water in the mineral oil lubricant. Therefore in addition to bearing corrosion, rusting may also be encountered.

It is an object of this invention, therefore, to provide an addition agent for mineral oil lubris cants which will prevent the formation of the engine deposits encountered in the use of mineral oil lub ricants.

It is a further object of this invention to provide addition agents for mineral oil lubricants which serve the functions of (1) inhibiting the corrosion of bearings, (2) inhibiting rusting, and (3) acting as a detergent to prevent ring sticking, the formation of engine deposits and to suspend or disperse very small particles of deterioration products or contaminating materials in the lubricant.

These and other objects are achieved by the present invention wherein asan addition agent 2 for mineral oil lubricants there is provided a salt having the following formula:

' OH on o o on on E-Qom-Q QonOE-Q i R i R wherein R. is an alkyl radical having from 4 to 12 carbon atoms, and M is a divalent metal. The above salts are excellent detergents and in many instances are remarkably eflective also for inhibiting bearing corrosion and rusting .in the use of mineral oil lubricants. Such salts, as well as the mineral oil lubricant compositions containing them, are believed to be novel and are considered part of our invention.

The salts of our invention are prepared by condensing equimolar proportions of formaldehyde, a divalent metal salt of a phenol having a para alkyl substituent of from 4 to 12 carbon atoms, and a phenol disulfide obtained by reacting two mols of a phenol having a para allwl substituent of from 4 to 12 carbon atoms with one moi of sulfur monochloride (S2012).

The divalent metal salts of the alkylated phenols used in preparing the addition agents of our invention are conveniently made by neutralizing the alkylated phenol with an oxide or hydroxide of the particular divalent metal desired. Alternatively, the alkali metal phenate of the phenol may first be made, and then the phenate may be reacted with a water-soluble salt of the divalent metal to yield the divalent metal salt of the phenol by a double decomposition reaction.

The phenol disulflde used in making our new addition agents is prepared by reacting two mols of the para alkyl phenol with one moi of sulfur monochloride according to the reaction:

OH QR S OH The reaction of the sulfur monochloride with the alkylated phenol may take, place at room temperature, and it usually is preferred to initiate the reaction at such temperature and then to raise the temperature to no higher than 350 F. to complete the reaction. However, the reaction may take place at any temperature ranging from room temperature to 350 F., provided care ls taken that the latter temperature is not exceeded. If the temperature of 350 F. is exceeded to any great extent, especially in the initial stages of the reaction, the product formed tends to be darkcolored and transmits to our new addition agent an undesirable dark-color and a tendency to be insoluble in mineral lubricating oils. The reaction of the para alkyl phenol with the sulfur monochloride may take place in the presence of an inert solvent, such as benzene, toluene, hexane, carbon tetrachloride, chloroform, cyclohexane, etc., to obtain a lighter-colored product. Also, the resulting phenol disulfide may be treated with an adsorbent clay, such as acid treated bentonite, in order to remove dark-colored byproducts.

The resulting phenol disulfide and the divalent metal salt of the para allwl phenol are then condensed with formaldehyde, all of the reactants being present in equimolecular proportions, with the splitting off of one mol of water. The condensation takes place upon heating, preferably to a temperature not greater than 275 F. In lieu of formaldehyde, formaldehyde-yielding compounds, such as trioxymethylene, paraformaldehyde and the like may be employed. Accordingly, as used in the appended claims, the term formaldehyde is intended to include such formaldelyde-yielding substances, as well as formaldehyde i self.

The phenols used in preparing both the divalent metal salt of the para alkyl phenol and the phenol disulfide are para alkyl substituted phenols having from 4 to 12 carbon atoms in the alkyl substituent. Thus the alkyl substituent may include normal or branched chain butyl, amyl, hexyl, heptyl, octyl, decyl and dodecyl radicals. A preferred alkyl substituent is the tetramethylbutyl radical. The para alkyl phenols are preferably obtained by alkylating in known manner, in the presence of sulfuric acid, phenol with oleflns having from' 4 to 12 carbon atoms. Olefins such as butene-l, isobutylene, the amylenes, di-isobutylene and tri-isobutylene may conveniently be employed. It is preferred to conduct the alkylation with di-isobutylene since the resulting product is primarily a para tetramethylbutyl phenol.

Any divalent metal may be used in forming the salt of the para alkyl phenol to yield excellent detergent compounds. Representative divalent metals include beryllium, calcium, barium, magnesium, strontium, zinc, stannous tin, copper, lead, cobalt and nickel. However, not all of the divalent metal salts of our invention confer bearing corrosion-inhibiting properties. Thus, copper and lead salts, although providing excellent detergent properties, are ordinarily not as useful as the other salts of our invention for inhibiting bearing corrosion. Accordingly, a preferred subgroup of the divalent metals is the alkaline earth metals, since the salts of these metals confer both detergent and corrosion-inhibiting properties. Stannous salts are also excellent for both purposes. our invention are excellent detergent agents, and therefore will confer at least detergent properties on mineral oil lubricants. If particular divalent metal salts which do not have good bearing corrosion-inhibiting properties are used in mineral However, all of the divalent metal salts of n 4. oil lubricants for their detergent effects, other materials, such as the calcium, barium and stannous salts of the present invention, or other known bearing corrosion inhibitors may be added to obtain the desired bearing corrosion-inhibiting effect.

The following examples further illustrate our invention. Unless otherwise stated, all parts are by weight.

Example I .-A divalent metal salt of para tetramethylbutyl phenol was first prepared by charging into an iron reaction vessel, equipped with an-agitator, reflux condenser and means for heating and cooling the charge, 4120 parts of para tetramethylbutyl phenol, 3150 parts of barium hydroxide (Ba(OHz).8H-:O) and 200 parts water. The mixture was agitated and heated to 210 F. for four hours and then cooled to F. A phenol disulfide was then prepared by charging into a separate similar reaction vessel 8240 parts of para tetramethylbutyl phenol and 8000 parts of hexane solvent. At 100 F., 270 parts of SzClz were added over a period of two hours. The temperature was then raised to F. and held at that point for eight hours. The phenol dissulfide reaction product in the solvent was then discharged into the first reaction vessel, containing the divalent metal salt of the phenol, and 1600 parts of an aqueous 37 per cent solution of formaldehyde were added. This mixture was refluxed for four hours and was then allowed to settle. The water layer was drawn of! and the solvent layer was filtered. The filtrate was then distilled to remove the solvent. The residue had the following properties:

Per cent Ash, as oxide 9.1 Sulfur 8.5

The salt obtained had the following formula:

on on o 0 on on I? i? s- CHFQ gen,- 3-- 1'; 1'; R a IL.

wherein R is the tetramethylbutyl radical.

Example II .Into an iron reaction vessel were charged 824 parts of para tetramethylbutyl phenol, 3000 parts of a solvent refined lubricating oil having a viscosity of SUV at 100 F., and 630 parts of barium hydroxide. The mixture was agitated and heated to 350 F. until no more water was distilled off. Into a separate vessel were charged 1648 parts of para tetramethylbutyl phenol, which was heated to F. Then 540 pounds of sulfur monochloride were added to the phenol over a period of four hours. The temperature was raised to 210 F. and held at thatpoint for ten hours. Then 200 parts of an adsorbent activated montmorillonite clay were added, the mixture stirred four hours at 220 F., and filtered. The filtrate was charged into the first reaction vessel, containing the lubricating oil solution of the barium salt of the phenol, and 320 parts of an aqueous 3''! per cent solution of formaldehyde were added. The mixture was refluxed for four hours and the temperature was then raised to 240 F. while applying a vacuum of 15 inches mercury to remove all the water added and formed in the reaction. The solution of the reaction product in the lubricating oil was filtered through a continuous filter. It had the following properties:

Gravity: API

18.7 Viscosity, SUV 100 F -4--- 1170 Color, NPA 3.0 Ash 4.6 Neutralization No. 11.! Sulfur, B per cent" 4.2

higher. This excellent solubility of our new addition agents enablesthe preparation of concentrated solutions thereof, as shown in Example 11 supra, which may then be diluted down to the proportion desired in the final mineral oil lubricant composition. As stated, our new addition agents confer excellent detergent eflects on the mineral lubricating oils with which'theyare incorporated, and in most instances confer in addition excellent bearing corrosion inhibiting and rust inhibiting properties. For these purposes our new addition agents are generally added to mineral oils in minor amounts, say from 0.1 per cent to 10.0 per cent by weight of the mineral oil, suilloient to confer improved detergent properties on the mineral lubricating oils with which they are incorporated. Generally, the addition of 1.0 per cent by weight of our new addition agents is suillcient to effect thede'sired improvement. In view of their high molecular weight and low volatility at high temperatures, our new addition agents are particularly advantageous for preparing lubricants which encounter high temperatures, such as aviation lubricating oils.

The following example illustrates the use of our new improvement agents to obtain improved mineral oil lubricant compositions.

Example [IL-Au improved aviation lubricating Oil was prepared by treating an aviation lumethod 257, Gulf," referred to in the foregoing example, is conducted as follows:

An alloy bearing shell oi certain commonly used standard dimensions is submerged in 300 cc. of the oil or oil composition to be tested in a 400 cc. Pyrex beaker and heated in a thermostatically controlled oil bath to 347 F. Air is then bubbled through the oil in' contact with the bearing shell at'a rate of 2000 cc. per hour. At the end of 48 hours,- the loss of weight and condition of the .bearing shell was determined, the bearing shell being washed free of oil and dried before weighing. When determining the effectiveness of various improvement agents, the usual procedure is to run a blank test simultaneously with the oil composition being tested, employing for that purpose a sample of the untreated oil. In this test it is advantageous. to employ commercial bearing shells. These shells comprise a suitable metal backing faced with the alloy bearing metal. In this way the actual bearing face is subjected to severe deterioration conditions. B comparison of the results of such tests with actual service tests, we have found them to be in substantial agreement as to the suitability of particular lubricants.

The Motor oil service test, method 259, Gulf, is fully described in U. S. Patent No. 2,378,442.

As shown in Example 111, the addition of the salt of Example I to mineral oil lubricant compositions resulted in excellent bearing corrosioninhibiting. rust-inhibiting and detergent properties. As shown under the Oxidation and bearing corrosion test, the corrosion of both copperlead and cadmium-silver alloys was completely eliminated. The remarkable detergent effects and corrosion test shows the effective rust inhibiting bricating oil stock with 3 per cent by weight of. the

additive prepared according to Example 1. A comparison of the properties of the base oil and I the improved oil follows:

corrosion test,

Unin hihiied abi Oil I on ravity, A PI. 24'. s 26. n Viscosity, SUV: 100 F. M8 1600 21') F 119.8 117.5 Viscosity Index 99 98 Flash, 0C "F 550 535 Fire, 00, F 600 000 Pour, l 0 0 Color, NPA'.I.... 4.75 4.75 Corrosion 'lcsl- ASIM 1) 665-44 '1 Distilled \Vater:

steel Rod, Appearance rusted bright Area Rusted, Per Cent 0 Oxidation dz Bearing Corrosion Test Method 257, Gulf:

Duration of Test, l'lr 48 48 Oil Bath 'lcmp., F.. 347 347 Air Rate, CcJHr 2000 9000 Quantity of Oil, Co 300 300 Heating Type Cu-Ph Oil-Pb Weight Change, l\lg 38.0 nil licaring Typle (id-Ag Cd-A a Weight C ange, Mg -54. 5 nil Motor Oil Sorvlce Test Mcihod 250, Gull:

Piston Condition Lacquer heavy very light OH OH O 0 OH OH S I V i I II nscm- -cn,- s-

' I 1 4 I I I R a a R R a properties.

While we have shown in the above example. the preparation of compounded lubricating oils, our invention is not limited thereto but comprises all mineral oil lubricant compositions containing our new addition agents, such as greases and the like.

We claim:

l. A salt having the formula:

wherein R is an alkyl radical having from 4 to 12 7 carbon atoms, and M is a divalent metal.

2. The salt of claim 1, wherein M is an alkaline earth metal.

3. Thea-$8."? of claim 1, wherein M is barium. 4. The salt of claim 1, wherein M is calcium. 5. The salt of claim 1, wherein M. is tin.

6. The salt of claim 1, wherein R is the tetrawherein R. is the tetramethylbutyl radicaL.

8. The process which comprises condensing equlmolar proportions of formaldehyde, a divalent metal salt of a phenol having a para walkyl substituent of from 4.to 12 carbon atoms, and a phenol disulfide obtained by reacting 2' mols of a phenol having a para alkyl substituent of from 4 to 12 carbon atoms with 1 mol of sulfur monochloride.

9. The process which comprises condensing at a temperature not greater than 275 F. 1 mol of formaldehyde with 1 mol of a divalent metal salt of a phenol having a para alkyl substituent of from 4 to 12 carbon atoms, and 1 mol of a phenol disulficle obtained by reacting at a temperature ranging from room temperature to 350 F. 2 mols of a phenol having a para alkyl substituent of from 4 to 12 carbon atoms with 1 mol of sulfur monochloride.

10. The process of claim 9, wherein the divalent metal salt is a barium salt, and the para alkyl substituent of the phenol is the tetramethylbutyl radical.

11. A lubricant composition comprising a major amount of a mineral lubricating oil and a minor amount. sufficient to confer detergent properties on the composition, of a salt having the formula:

M OH OH O O OH OH ISI 5 Os- C1170 0H? I;

R R R R R wherein R is an alkyl radical having from 4 to 12 carbon atoms, and M is a divalent metal.

12. The composition of claim 11, wherein M is an alkaline earth metal.

13. The composition of claim 11, wherein M is barium.

14. The composition of claim 11, wherein M calcium.

15. The composition of claim 11, wherein M is tin.

16. The composition of claim 11, wherein R is the tetramethylbutyl radical.

17. The composition of claim 11, wherein the metal salt is present in an amount of from 0.1 to 10.0 per cent by weight on the mineral oil.

.18. A lubricant composition comprising a major amount of a mineral lubricating oil and a minor amount, from 0.1 to 10.0 per cent by weight on the mineral lubricating oil, of a salt having the formula:

OH OH O O OH. OH

i f? S CH: CH -S l t it B. R

wherein R is the tetramethylbutyl radical and M is a divalent metal.

19. The composition of claim 18, wherein M is barium.

20. The composition of claim 18, wherein M is calcium.

21. The process which comprises condensing at a temperature not greater than 275 F. in a mineral lubricating oil 1 mol of formaldehyde with 1 mol of a divalent metal salt of a phenol having a para alkyl substituent of from 4 to 12 carbon atoms, and 1 mol of a phenol disulfide obtained by reacting at a temperature ranging from room temperature to 350 F. 2 mols of a phenol having a para alkyl substituent of from 4 to 12 carbon atoms with 1 mol of sulfur monochloride and recovering in solution in said mineral lubricating oil a salt having the formula:

M on on o o 011 on s era-O Oomsit R R R a wherein R is an alhl radical having from 4 to 12 carbon atoms and M is a divalent metal.

I HERSCHEL G. SMITH. TROY L. CANTRELL. JOHN G. PETERS.

"REFERENCES CITED The following references are of record in the 

